An optical time-domain reflectometer (OTDR) is a useful tool for testing point-to-point fiber optic links, testing passive optical networks (PONs), and finding faults, such as breaks and measure reflectance or optical return loss (ORL) in fiber optic networks. The OTDR generates output pulses and measures the return signal from the same end of the fiber network under test.
A current standard method for using an OTDR to test a multi-fiber cable 32 terminating in an MPO connector 34 is illustrated in FIG. 2A. The MPO connector 34 is plugged into a breakout assembly 100 that optically connects each fiber strand within the multi-fiber cable 32 with a separate optical fiber strand 102 within the breakout assembly 100. These optical fiber strands 102 within the breakout assembly 100 then emerge from the other side of the breakout assembly 100 and each strand 102 ends in a single fiber connector 104 after a short distance from their exit from the breakout assembly 100. An OTDR cable 106 as long as 500 feet may extend from an OTDR 50 and end in a port 108 that accepts the single fiber connector 104 that terminates each of the fiber strands 102 extending from the breakout assembly 100. A user would plug the MPO connector 34 of the multi-fiber cable 32 being tested into the breakout assembly 100; plug the single fiber connector 104 into the port 108 of the cable 106 extending from the OTDR 50; and then operate the OTDR 50.
The user would repeat this process for all of the strands extending from the breakout assembly. This may be as few as two, and as many as twenty-four or more. The user must be careful to not mix up the strands that have been tested with those that haven't, and keep careful track of which strand is which so the user knows which strand within the multi-fiber cable is being tested. This is an unwieldy and confusing assembly and process. Moreover, because of the short distance between the connection of the multi-fiber cable 32 being tested with the breakout assembly 100 and the connection of the single fiber connector 104 with the OTDR cable 106, the OTDR 30 cannot accurately test the connector loss of the end MPO connector 34 of the multi-fiber cable 32 under test that is connected to the breakout assembly 100. Because the connector 34 under test and the single fiber connector 104 are so close in distance, the OTDR will read the connector loss of both connections as one big loss, and it is impossible to attribute the correct amount of that loss to the test connector 34 alone. In essence, the OTDR 30 cannot “see” that end connector 34 of the cable under test 32 when it is so close to another connection, such as single fiber connector 104. One solution to this problem might be to make the fiber strands 102 extending from the breakout assembly 100 at least 100 feet long. This would only make the already unwieldy assembly more unwieldy, however.
Current art does have a solution to the problem of having to check each strand extending from the breakout assembly, strand by strand, in the correct order. All of the strands extending from the breakout assembly may be brought back together to terminate in an MPO connector that is then plugged into an MPO switch, which is connected to the OTDR. The MPO switch can automatically direct the pulses coming from the OTDR into the separate strands, so that the user may test each of the individual strands of the multi-fiber cable connected to the breakout assembly without having to physically connect, strand by strand. Not only is this time-saving and less confusing, but it also avoids connector damage from repeated connecting and disconnecting. The use of an MPO switch does not solve the problem of the OTDR not being able to see the end connector of the multi-fiber cable under test, however.
Therefore, there is a need for an improved assembly that is both easy to use and that allows the OTDR to test the end connector of a cable under test.